The present invention relates to an eye""s optical characteristic measuring system, by which it is possible to estimate and calculate a visual acuity of an eye under testing based on a light amount intensity distribution characteristic of an index image projected on a fundus of the eye under testing.
In the past, the present applicant has already filed a patent application on a system, which comprises a target projection system for projecting an index image to a fundus of an eye under testing and a photodetection optical system for guiding the index image toward a photoelectric detector, in which a simulation image on the fundus of the eye is calculated, which may be formed when the target image is projected on the fundus of the eye under testing, based on a light amount intensity distribution of the index image detected at the photoelectric detector. By this system, based on a result of the calculation, it is possible to detect which kind of image is formed on the fundus of the eye under testing.
In this system, it is possible to calculate under which condition various kinds of the target images are projected to the fundus of the eye under testing without actually projecting various kinds of the target images.
However, in the system proposed in the above patent application, it is advantageous in that the image itself obtained by simulation can be observed, while, with respect to the visual acuity value of the eye under testing, the tester must estimate the visual acuity value from the result of the observation. In this respect, there has been a problem in that it is difficult to obtain the accurate visual acuity value.
It is an object of the present invention to provide an eye""s optical characteristic measuring system, by which it is possible to solve the problem of the conventional type eye""s optical characteristic measuring system and to obtain an objectively accurate visual acuity value from the measured data without asking the person under testing about the result of visual observation.
To attain the above object, the eye""s optical characteristic measuring system according to the present invention comprises an index projection system for projecting an index image on a fundus of an eye under testing, a photodetection optical system for guiding the index image toward a photoelectric detector, a simulation image calculating unit for calculating each of images of target images formed when a plurality of target images different in size are respectively projected on the fundus of the eye under testing based on a light amount intensity distribution of the index image detected on the photoelectric detector, and a visual acuity calculating unit for calculating a visual acuity value of the eye under testing, wherein the simulation image calculating unit calculates light amount intensity distributions in each of predetermined meridian directions of the images of the target images, and the visual acuity calculating unit detects a plurality of light amount intensity distribution values based on the light amount intensity distributions and calculates the visual acuity value of the eye under testing based on the plurality of light amount intensity distribution values. Further, the present invention provides the eye""s optical characteristic measuring system as described above, wherein the light amount intensity distribution characteristic value is detected based on each light amount distribution in a plurality of the predetermined meridian directions of the image of the each target image, and the visual acuity value of the eye under testing is calculated based on the values of light amount intensity distribution characteristic in the plurality of the predetermined meridian directions. Also, the present invention provides the eye""s optical characteristic measuring system as described above, wherein the visual acuity value of the eye under testing is calculated from an average value of the light amount intensity distribution characteristic values obtained in each of the predetermined meridian directions. Further, the present invention provides the eye""s optical characteristic measuring system as described above, wherein a light amount intensity distribution characteristic value-visual acuity curve is obtained by interpolating a plurality of light amount intensity distribution characteristic values in the predetermined meridian direction and the visual acuity value of the eye under testing is calculated based on the light amount intensity distribution characteristic value-visual acuity curve. Also, the present invention provides the eye""s optical characteristic measuring system as described above, wherein the light amount intensity distribution characteristic value of the image of the target image is a contrast value. Further, the present invention provides the eye""s optical characteristic measuring system as described above, wherein the light amount intensity distribution characteristic value of the image of the target image is a depression value. Also, the present invention provides the eye""s optical characteristic measuring system as described above, wherein at least one gap is formed in the target image, and the predetermined meridian direction is a direction to traverse the gap of the image of the target image.